Move the awaitEvent declaration into IOManager.h

And add or adjust comments at the use sites of awaitEvent.

5 files changed, 36 insertions, 35 deletions

diff --git a/rts/AwaitEvent.h b/rts/AwaitEvent.h
deleted file mode 100644
index 92848addf2..0000000000
--- a/rts/AwaitEvent.h
+++ /dev/null
@@ -1,21 +0,0 @@
-/* -----------------------------------------------------------------------------
- *
- * (c) The GHC Team 1998-2005
- *
- * The awaitEvent() interface, for the non-threaded RTS
- *
- * -------------------------------------------------------------------------*/
-
-#pragma once
-
-#if !defined(THREADED_RTS)
-/* awaitEvent(bool wait)
- *
- * Checks for blocked threads that need to be woken.
- *
- * Called from STG :  NO
- * Locks assumed   :  sched_mutex
- */
-RTS_PRIVATE void awaitEvent(bool wait);  /* In posix/Select.c or
-                                          * win32/AwaitEvent.c */
-#endif
diff --git a/rts/IOManager.h b/rts/IOManager.h
index 80ef84b7c2..fe65f373da 100644
--- a/rts/IOManager.h
+++ b/rts/IOManager.h
@@ -149,6 +149,20 @@ void insertIntoSleepingQueue(StgTSO *tso, LowResTime target);
 INLINE_HEADER bool anyPendingTimeoutsOrIO(CapIOManager *iomgr);
 
 
+#if !defined(THREADED_RTS)
+/* Check whether there is any completed I/O or expired timers. If so,
+ * process the competions as appropriate, which will typically cause some
+ * waiting threads to be woken up.
+ *
+ * Called from schedule() both *before* and *after* scheduleDetectDeadlock().
+ *
+ * Defined in posix/Select.c
+ *         or win32/AwaitEvent.c
+ */
+void awaitEvent(bool wait);
+#endif
+
+
 /* Pedantic warning cleanliness
  */
 #if !defined(THREADED_RTS) && defined(mingw32_HOST_OS)
diff --git a/rts/Schedule.c b/rts/Schedule.c
index 2b25c96b71..7f9433c0ec 100644
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -30,7 +30,6 @@
 #include "Sparks.h"
 #include "Capability.h"
 #include "Task.h"
-#include "AwaitEvent.h"
 #include "IOManager.h"
 #if defined(mingw32_HOST_OS)
 #include "win32/MIOManager.h"
@@ -317,6 +316,9 @@ schedule (Capability *initialCapability, Task *task)
         /* Notify the I/O manager that we have nothing to do.  If there are
            any outstanding I/O requests we'll block here.  If there are not
            then this is a user error and we will abort soon.  */
+        /* TODO: see if we can rationalise these two awaitEvent calls before
+         *       and after scheduleDetectDeadlock().
+         */
         awaitEvent (emptyRunQueue(cap));
 #else
         ASSERT(sched_state >= SCHED_INTERRUPTING);
@@ -900,17 +902,23 @@ static void
 scheduleCheckBlockedThreads(Capability *cap USED_IF_NOT_THREADS)
 {
 #if !defined(THREADED_RTS)
-    //
-    // Check whether any waiting threads need to be woken up.  If the
-    // run queue is empty, and there are no other tasks running, we
-    // can wait indefinitely for something to happen.
-    //
-    // TODO: this empty-queue test is highly dubious because it only makes
-    // sense for some I/O managers. The sleeping_queue is _only_ used by the
-    // select() I/O manager. The WinIO I/O manager does not use either the
-    // sleeping_queue or the blocked_queue, so both queues will _always_ be
-    // empty and so awaitEvent will _never_ be called here for WinIO. This may
-    // explain why there is a second call to awaitEvent below for mingw32.
+    /* Check whether there is any completed I/O or expired timers. If so,
+     * process the competions as appropriate, which will typically cause some
+     * waiting threads to be woken up.
+     *
+     * If the run queue is empty, and there are no other threads running, we
+     * can wait indefinitely for something to happen.
+     *
+     * TODO: see if we can rationalise these two awaitEvent calls before
+     * and after scheduleDetectDeadlock()
+     *
+     * TODO: these empty-queue tests are highly dubious because they only make
+     * sense for some I/O managers. The sleeping_queue is _only_ used by the
+     * select() I/O manager. The WinIO I/O manager does not use either the
+     * sleeping_queue or the blocked_queue, so both queues will _always_ be
+     * empty and so awaitEvent will _never_ be called here for WinIO. This may
+     * explain why there is a second call to awaitEvent below for mingw32.
+     */
     if (anyPendingTimeoutsOrIO(cap->iomgr))
     {
         awaitEvent (emptyRunQueue(cap));
diff --git a/rts/posix/Select.c b/rts/posix/Select.c
index f02fd63981..6c357a9982 100644
--- a/rts/posix/Select.c
+++ b/rts/posix/Select.c
@@ -19,7 +19,7 @@
 #include "RtsUtils.h"
 #include "Capability.h"
 #include "Select.h"
-#include "AwaitEvent.h"
+#include "IOManager.h"
 #include "Stats.h"
 #include "GetTime.h"
 
diff --git a/rts/win32/AwaitEvent.c b/rts/win32/AwaitEvent.c
index 6a621d6ef5..a8bb3cd191 100644
--- a/rts/win32/AwaitEvent.c
+++ b/rts/win32/AwaitEvent.c
@@ -16,7 +16,7 @@
 #include "Rts.h"
 #include "RtsFlags.h"
 #include "Schedule.h"
-#include "AwaitEvent.h"
+#include "IOManager.h"
 #include <windows.h>
 #include "win32/AsyncMIO.h"
 #include "win32/AsyncWinIO.h"